Members of Dirent structure

Question

I have started working with dirent.h library and I came across a very useful member of "struct dirent" structer which struct dirent *p->d_name in my book. But unfortunatly it doesn't states any other members of this structure;

I was wondering what else are the members of this structure and what are they used for?

Regards

Duncandunce

I assume you're on Linux. In that case, simply read the dirent.h manual page (man dirent.h). – Wingo

@NikosC. No manual entry for dirent.h – Fernando

@Fernando You're missing the POSIX man-pages package. (Whatever it's called in your Linux distro. On mine (Gentoo), it's sys-apps/man-pages-posix). – Wingo

@NikosC. wow, I never knew that here's more than the default manual pages. Indeed, on my Kubuntu it was the package manpages-posix-dev. – Fernando

Answer 1

The structure, struct dirent refers to directory entry.

http://www.gnu.org/software/libc/manual/html_node/Directory-Entries.html

In linux it is defined as:

struct dirent {
    ino_t          d_ino;       /* inode number */
    off_t          d_off;       /* offset to the next dirent */
    unsigned short d_reclen;    /* length of this record */
    unsigned char  d_type;      /* type of file; not supported
                                   by all file system types */
    char           d_name[256]; /* filename */
};

refer: man readdir

Or just look for "dirent.h" in the include directory.

Bringhurst

As written in another answer, only d_ino and d_name are POSIX. The rest should be avoided, or at worse used very cautiously, and only if you understand the implications. – Tellez

The rest of the fields are needed just for extremely simple things (like determining if an entry refers to a file or a sub-directory), and telling people not to use any of the other fields is pointless (because they almost always must use them). – Disquieting

Answer 2

There are only two members (from wikipedia):

• ino_t d_ino - file serial number
• char d_name[] - name of entry (will not exceed a size of NAME_MAX)

Take a look at the unix spec as well.

Marchioness

There might be some other (implementation or system specific) members, but you should not use them for POSIX portability reasons. – Immersion

Answer 3

in addition to above answer of @Binyamin Sharet:

 off_t d_off - file offset
    unsigned short int d_reclen - length of the dirent record
    unsigned short int d_namlen - length of name
    unsigned int d_type - type of file

Illassorted

These should not be used. They are implementation-specific and not defined by POSIX. You should probably update your answer to reflect that. – Wingo

some filesystems (e.g. ext4, xfs) in some configurations (usually at mkfs time) can deliver the type of (some or all) the directory entries (the DT_* symbols). If not known, they are DT_UNKNOWN. The d_type member is not portable, but nevertheless widely available. – Bessbessarabia